1. Field of the Invention
This invention relates to the improvement of a linear bearing to be used for the sliding surface of the table saddle and machining center in a machine tool, or for the portion of a conveyor apparatus where heavy objects are to be borne and reciprocated.
2. Background of the Invention
A ball bush is widely known as a linear bearing. Against a rising load, however, the ball bush can bear only a small load though it can withstand a radial load. A linear bearing having a larger contact surface between balls and rail is disclosed in U.S. Pat. No. 4,040,679 which is of the same inventor as the present inventor.
In the bearing body disclosed in the said patent there are formed, in its inner peripheral surface, rolling surfaces for guide of balls, namely a plurality of recesses for loaded and unloaded balls, and also peripheral grooves adjacent both ends thereof, while formed in the retainer are a plurality of annular grooves in correlation with the recesses and peripheral grooves formed in the bearing body. However, such bearing body and retainer are so complex in shape that they require an increased number of manufacturing steps, which leads to an increase in cost.
As a result of extensive studies for attaining the mass production and reduction of cost of a linear bearing, I have found that the number of manufacturing steps can be decreased and manufacturing time shortened by dividing a linear bearing into three portions, namely a bearing body and two side covers which are secured to both ends of the bearing body, and further by forming slits in the recess of a retainer which guides and supports loaded balls, with tongue pieces formed at both ends of each said slit.